U.S. Postal Service worker Joshua Crowell recently began noticing "2020 graduate" lawn signs outside some homes along his route in New Hampshire. He felt bad for the high school seniors who are missing out on the chance to walk across the graduation stage and receive their diplomas due to the coronavirus crisis, so he decided to drop something special in their mailboxes to brighten their day.

Crowell, who said he has been delivering mail throughout the pandemic, told CBS News that he was moved by the signs and thought of his own two children, "working really hard to graduate and then not be able to have that chance to walk with their class."

"I just said to myself, 'I should get those students a graduation card and maybe put a gift card inside,'" Crowell said.

So, he bought a bunch of greeting cards and $5 Dunkin' gift cards, and then got to work writing messages to the graduates.

Crowell says he has left "at least 25 cards" so far, but plans to keep delivering more throughout the summer.

"I always keep a few extra in my lunchbox so, as I'm doing a route and I see a sign, I throw a stamp on it and put it in their mailbox," he said. "I hope that they are thankful that someone is thinking about them."

The postal worker, who has been on the job for about six months, told CBS News he is buying the gift cards himself. "I don't have a lot of money, but I am paying for these out of my own pocket," he explained.

Crowell's kind gesture has made an impact on many of the graduates, and he has received multiple thank you cards in return.

"Thank you so much for the gift card," one note read. "Your good deed meant so much to me and absolutely made my week."

The graduates also thanked Crowell for being an essential worker.

"Thank you for all you do, not only for us, but the whole community," read another letter. "You are so appreciated!"

Many high school and college graduation ceremonies throughout the country have been canceled or postponed. But educators, parents and public figures have been doing their best to celebrate the accomplishment for graduating seniors.

One college senior's family held a ceremony in the driveway of their home, complete with a rented stage and podium. Many cities and towns are holding car parades and other socially distant events to ensure the students feel special. On Saturday night, some of the world's most famous faces came together for a primetime graduation special for the class of 2020.